O-(2,5 - dichloro-4-alkylmercaptophenyl) thionophosphates and thionophosphonates

ABSTRACT

THE COMPOUNDS ARE 0-(2,5-DICHLORO-4-ALKYLMERCAPTOPHENYL)-THIONOPHOSPHATES AND ANALOGOUS THIONPHOSPHONATES, USEFUL AS INSECTICIDES AND ACARICIDES.

Patented Aug. 17, 1971 3,600,472 -(2,5 DICHLORO-4-ALKYLMERCAPTOPHENYL) IEI AIIQEEMPHOSPHATES AND THHONUPHUSPHU- T Richard Sehring and Wolfgang Buck, lingelheirn (Rhine),

Germany, assignors to C. H. Boehringer Sohn, Engelheim (Rhine), Germany No Drawing. Filed Nov. 15, 1967, fier. No. 683,125 Claims priority, application Germany, Nov. 22, 1966, B 89,951; July 11, 1967, B 93,427 Int. Cl. Atlln 9/36; C07f 9/18, 9/40 US. Cl. 260-949 8 Claims ABSTRACT OF THE DISCILGSURE The compounds are O-(2,5-dichloro-4-alkylmercaptophenyl) thionophosphates and analogous thionophosphonates, useful as insecticides and acaricides.

THE PRIOR ART German Pat. No. 1,116,656 discloses 0,0-dialkylO-(3- alkyl-4-alkylmercapto-phenyl) thionophosphates having insecticidal and acaricidal properties.

This invention relates to novel thionophosphates and thionophosphonates and to a novel process for preparing these compounds, as well as to novel 2,5-dichloro-4-alkylmercapto-phenol starting compounds.

More particularly, the present invention relates to O-alkyl O (2,5 dichloro 4 alkylmercapto-phenyl)- thionophosphates and analogous thionophosphonates of the formula f1 M0) o-s R3 wherein R is alkyl of 1 to 4 carbon atoms,

R is alkyl to 1 to 3 carbon atoms or phenyl, R is alkyl of 1 to 4 carbon atoms, and

n is 0 or 1.

A compound of the Formula I is prepared in accordance with the present invention by reacting a salt, preferably an alkali metal or ammonium salt, of a 2,5-di-chloro- 4-alkylmercapto-phenol of the formula wherein R has the same meanings as in Formula I, with a phosphorus compound of the formula R (O) Hal (III) alkyl-substituted phenol with a dialkyl disulfide in the presence of fullers earth or of at least an equimolar amount of a condensation agent of the Friedel-Crafts type.

German Pat. No. 1,063,177 discloses a process for the preparation of hydroxyarylalkyl-thioethers which comprises reacting a monocyclic or bicyclic phenol which may be alkyland/or halo-substituted and has at least one free por o-position with respect to the phenolic hydroxyl group with an alkylsulfenyl chloride at a temperature up to about 30 C., the alkylsulfenyl chloride is formed in situ in the reaction mixture from a dialkyl disulfide 0r alkylthio and sulfuryl chloride.

Finally, German Pat. No. 1,088,980 describes the preparation of aromatic-aliphatic hydroxythioethers by reacting an aliphatic sulfoxide with a phenol in the presence of hydrogen chloride or thionyl chloride, and cleaving the sulfonium salt formed thereby in customary fashion to obtain the desired aromatic-aliphatic hydroxy-thioether.

All of these prior art processes, however, produce only moderate yields of the desired hydroxyaryl-thioethers.

We have discovered that a 2,5-dichloro-4-alkyl-mercaptophenol may be obtained with very good yields from an alkyl-(2,4,5-trichloro-phenyl)-sulfide under alkaline ether cleavage conditions. The reaction in accordance with the presence invention proceeds pursuant to the following reaction equation.

NaOH I G1 S R l10- SR Methanol elevated 6 O1 temperature 1 wherein R has the same meanings as in Formula I. Our discovery is unexpected and surprising in view of the fact that it is well known that 2,4,5-trichloro-anisole is transformed into 2,4,5-trichloro-phenol in hot methanolic alkali pursuant to the following reaction equation:

NaOH Ol- --OCH --1 01 OH Methanol I O C1 01 Thus, it could not have been foreseen that the analogous alkylthioether would not undergo cleavage of the ether linkage under similar conditions.

The alkyl (2,4,5 trichloro phenyl) sulfides required as starting compounds for the novel process according to the present invention may be prepared by well known methods, such as by reducing trichlorobenzene sulfochloride with nascent hydrogen generated by zinc and hydrochloric acid, followed by alkylation.

German Pat. No. 1,116,656 describes the preparation of O (methylmercapto substituted phenyl) 0,0-dialkyl-thionophosphates in an anhydrous medium. We have further discovered that excellent yields of the novel 0,0- dialkyl-O-(2,5 dichloro 4 alkylmercapto phenyl)- thionophosphates according to the present invention may also be obtained by reacting a 2,5-dichloro-4-alkylmercapto-phenol with an 0,0-dialkyl-thionophosphoric acid halide in aqueous solution.

In comparison to the process described in German Pat. No. 1,116,656, the process according to the present invention is considerably simpler and more economical. It is not possible, however, to apply the process for the preparation of the compounds pursuant to the present invention in an aqueous medium to those described in German Pat. No. 1,116,656 without sacrificing a significant amount of the yield. For instance, the yield of 0,0- dimethyl O (4 methylmercapto 3 methyl phenyl)- thionophosphate in an anhydrous medium is in excess of 90% of theory, whereas the yield in an aqueous medium is barely 70% of theory.

The following examples further illustrate the present invention and will enable others skilled in the art to understand it more completely. It should be understood, however, that the invention is not limited solely to the particular examples given below.

EXAMPLE 1 Preparation of 2,5-dichloro-4-methylrnercapto-phen0l A mixture of 455 gm. of 2,4,5-trichloro-anisole, 370 gm. of an aqueous 48% sodium hydroxide solution and 1 liter of methanol was heated for six hours at 160 C. in an autoclave. Thereafter, the reaction mixture was vacuum filtered, the methanol was distilled out of the filtrate, and the distillation residue was diluted with water. The dilute aqueous solution was filtered through charcoal, the filtrate was acidified with concentrated hydrochloric acid, and the acid solution was extracted with methylene chloride. The extract solution was dried over sodium sulfate, and the methylene chloride was distilled off, leaving as a residue 355 gm. (85% of theory) of 2,5 dichloro 4 methylmercapto phenol, B.P. 110 C. at 0.05 mm. Hg. After recrystallization from benzene the product had a melting point of 1101l2 C.

Analysis.Calculated (percent): CI, 33.9; S, 15.30. Found (percent): CI, 33.8; S, 15.34.

EXAMPLE 2 Preparation of 0,0-diethy1-O-(2,5-dichloro-4-methylmercapto-phenyl) -thionophsphate 188 gm. (1.1 mols) of 0,0-diethyl-thionophosphoric acid chloride were slowly added dropwise at 60 C. to a mixture of 209 gm. (1 mol) of 2,5-dichloro-4-methylmercapto-phenol, 40 gm. of sodium hydroxide and 150 cc. of water. The resulting mixture was stirred for three hours at 60 C., and then 100 cc. of 2 N sodium hydroxide were added thereto, and the mixture was allowed to cool. Thereafter, the aqueous phase was separated and extracted several times with toluene. The organic extract solutions were combined, dried over sodium sulfate, and the toluene was distilled off. 332 gm. (92% of theory) of 0,0 diethyl O (2,5 dichloro-4- methylmercapto phenyl) thionophosphate, HP. 150- 151 C. at 0.001 mm. Hg, of the formula P H5020 OQ-S on I Cl were obtained.

Analysis.-Calculated (percent): C, 36.52; Cl, 19.32. Found (percent): C, 36.60; Cl, 19.41.

EXAMPLE 3 Preparation of 0,0-dimethyl-O(2,5-dichloro-4-methylmercapto-phenyl) -thionopho sphate moo o-Q-s on.

were obtained by reacting one mol of 2,5-dichloro-4- methylmercapto-phenol with one mol of 0,0-dimethylthionophosphoric acid chloride in water.

4 Analysis.Calculated (percent): C, 33.21; Cl, 21.32. Found (percent): C, 33.19; C], 21.30.

EXAMPLE 4 Preparation of O-n-propyl-O- (2,5-dichloro-4-methy1- mercapto-phenyl) -methyl-thionophosphonate 10 gm. (0.048 mol) of 2,5-dichloro-4-methylmercaptophenol were dissolved in a solution of 1.92 gm. (0.048 mol) of caustic soda in 8 cc. of 'water at 50 C., and 8.3 gm. (0.048 mol) of methyl-thionophosphoric acid-npropyl ester chloride were added dropwise to the solution while stirring. The reaction mixture was then stirred for four hours at 60 C. and thereafter cooled, and the precipitated oil was taken up in 50 cc. of ether. The ethereal solution was extracted with 1 N sodium hydroxide and water, and the ether was evaporated. The residue was freed from volatile components by vacuum distillation at C. and 0.1 mm. Hg. 12.2 gm. (73.5% of theory) of a slightly reddish oil were obtained, which was identified to be O-n-propyl-O-(2,5-dichloro-4-methylmercaptophenyl)-methyl-thionophosphonate of the formula on, O-Q-S on;

EXAMPLE 5 Using a procedure analogous to that described in Example 4, O-ethyl-O-(2,5-dichloro-4-methylmercapto-phenyl)-ethyl-thionophosphonate, a yellow oil, of the formula l Cl was prepared from 2,5-dichloro-4-methylmercapto-phemol and ethyl-thionophosphonic acid-ethyl ester chloride. The yield was 74% of theory.

EXAMPLE 6 Using a procedure analogous to that described in Example 4, O-ethyl-O-(2,5-dichloro-4-methylmercapt0-phen yl)-phenyl-thionophosphonate, M.P. 9294 C., of the formula EXAMPLE 7 Using a procedure analogous to that described in Example 4, O-methyl-O-(2,5 dichloro-4-methylmercaptophenyl)-ethyl-thionophosphonate, M.P. 6465 C. of the formula 01 /P\ I Inc. o-sorn was prepared from 2,5-dichloro-4-methylmercapto-phenol and ethyl-thionophosphonic acid-methyl ester chloride. The yield was 73.4% of theory.

EXAMPLE 8 Using a procedure analogous to that described in Example 2, 0,0-diethyl-O-(2,5-dichloro-4-isopropylmercaptophenyl)-thionophosphate, a light yellow oil, of the formula was prepared from 2,5-dichloro-4-isopropylmercapto-phenol and 0,0-diethyl-thionophosphoric acid chloride. The yield was 92% of theory.

EXAMPLE 9 Using a procedure analogous to that described in Example 2, 0,0-diethyl-O-(2,5-dichloro-4-n-butylmcrcaptophenyl)-thionophosphate, a light yellow oil, of the formula was prepared from 2,S-dichloro-4-n-butylmercapto-phenol and 0,0-diethyl-thionophosphoric acid chloride. The yield was 90% of theory.

The compounds of the Formula I above have useful pesticidal properties. More particularly, they exhibit insecticidal and acaricidal activities and are especially eifective for the eradication of plant lice (aphids), spider mites, houseflies, bedbugs and the like, and in this respect they are far superior to the analogous compounds described in German Pat. No. 1,116,656, as the following comparisons show:

Effectiveness against (in ppm.)-

is then disseminated in the area infested with the insects or acarids to be eradicated by spraying, painting or scattering. The preferred concentration of the active insecticidal ingredient in such compositions is from 0.01 to 3% by weight, based on the total weight of the composition.

For instance, an elfective insecticidal dusting powder is obtained by spraying two parts by weight of a compound of the Formula I onto 98 parts by weight of kaolin, and milling the mixture into a fine homogeneous powder.

Similarly, a wettable powder is obtained by spraying 25 parts by weight of a compound of the Formula I onto 73 parts by weight of kieselguhr, adding thereto 2 parts by weight of naphthalene sodium sulfonate, and milling the mixture into a fine homogeneous powder, which is then admixed with water until the desired active ingredient concentration is achieved. The resulting aqueous suspension is an effective insecticidal composition.

Finally, an emulsion is obtained by dissolving 20 parts by weight of a compound of the Formula I in 75 parts by weight of xylene, and adding 5 parts by weight of ricinoleic acid butyl ester sulfonate to the solution. The emulsion is then diluted with 'water until the desired active ingredient concentration is achieved. The aqueous suspension is an effective insecticidal composition.

While the present invention has been illustrated with the aid of certain specific embodiments thereof, it will be readily appreciated by others skilled in the art that the invention is not limited to these particular embodiments, and that various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.

We claim:

1. A compound of the formula wherein R and R are each alkyl of 1 to 4 carbon atoms,

2. A compound of the formula Plant lice (aphids) Spider mites Hous efiies B edbugs Compound EDso EDsO EDsn EDga EDw EDps EDas 0.9 4.3 0.9 1.2 3.6 0.003 1. 0 s. 0 0. 003 0. 001 3. 3 9 7 1.95 as 11.3 0.008 0.000

1 After minutes. 2 One day.

The above comparative data show that the compounds according to the present invention are several times more wherein etfective than the closely related compound of the German patent.

For insecticidal or acaricidal purposes the phosphorus compounds of the present invention are admixed with a customary solid or liquid carrier to form such conventional pesticidal compositions as solutions, suspensions, dusting powders, pastes or the like, and the composition R is alkyl of 1 to 3 carbon atoms,

R is methyl, ethyl or phenyl,

R is alkyl of 1 to 4 carbon atoms, and n is 0 or 1.

3. A compound according to claim 2, wherein R is n-propyl, R and R are methyl, and n is 0.

4. A compound according to claim 2, wherein R and R are ethyl, R is methyl, and n is 0.

7 8 5. A compound according to claim 2, wherein R is FOREIGN PATENTS y 2 18 P 31 s 18 methyl, 15 42 40 5 1959 Australia 2 0 .949

6. A compound according to claim 2, wherein R and R37ar2methy1, zd y 2 h R R CHARLES B. PARKER, Primary Examiner compoun accor mg 0 c aim w erem 2 5 and R3 are methyl and n is L R. L. RAYMOND, Asslstant Examlner 8. A compound according to claim 2, wherein R and U S cl XR R are ethyl, R is methyl, and n is 1.

260-6091 973; 424216 References Cited 10 UNITED STATES PATENTS 3,042,703 7/1962 Schegk et a1. 260-949 (2 33? U mm) sums PA'JEN'I or; P101; CE iTIFICATE CF CORRECTION Patent No. 3, 7

Dated August 17, 1971 hummus) RICHARD SEHRING and WOLFGANG'BUCK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

- Column 1, line 58; that portion of the formula readingcolumn a, line 67; 's P should read Columh 5,' lin'e 7; v

' Colfiinn 5, line '9: that portion of the formuia reading -sca (cn I 4 should; read I. r

Signed and sealed this" 28th day of March l972.

(SEAL) ,Attest:

EDWARD M.FLETCHER-,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner pi .Patents 

